Soap antioxidant



Patented May 8, 1945 soar ANTIOXIDANT Elmer w. Cook, New York, N. Y., assignor to American Cyanamid Company,

New York,

N. Y., a corporation of Maine No Drawing. Application March 2, 1944, Serial No. 524,780

2 Claims.

This invention relates to an improvement in soap and soap products, and more particularly to the stabilization of. soap against discoloration and rancidity upon storage. By "soap I mean ordinary commercial soap, which is an alkali metal salt of a fat acid such as is obtained by the saponiflcation of vegetable or animal fats of the type of tallow, coconut oil and the like.

I have-found that the biguanide andhydrocarbon-substituted biguanide salts of p-tertiary amylphenyl phosphoric acids are improved soap stabilizers and will prevent discoloration and rancidity in soap to a markeddegree. Accordingly, my invention consists in the stabilization of soap against discoloration and rancidity by incorporating therein small but effective amounts of a biguanide p-tertiary 'amylphenyl phosphate. I have found'that a high degree of stabilization is obtained when amounts on the order' of 0.01-0.5% of my new stabilizer are used, based on the weight of the soap.

,Biguanide itself and such substituted biguanides as mono-orthotolyl biguanide, mono-phenyl biguanide, mono-xylyl biguanide and bi-phenyl biguanide have hitherto been used as soap stabilizers, either as such or in the form of salts with hydrochloric acid. However, the hydrochlorldes and other simple salts'of these biguanide compounds are no better stabilize'rsthan are the biguanides themselves. It is therefore quite surprising to mid that the p-tertiary amylphenyl phosphate salts of these biguanides improved soap st bilizing properties, for the alkali metal and other simple salts of p-tertiary amylphenyl phosphate possess little or no soap stabilizing properties.

The p-tertiary'amylphenyl phosphoric acids are prepared by reacting p-tertiary amylphenol with mos. Either the monoor the diester may be prepared in this manner and used to form a biguanide or hydrocarbon-substituted biguan- 'ide salt. Preferably I prepare a mixture of monoand diesters by heating 1 mole of phosphorous pentoxide with 3 moles of p-tertiary amylphenol with stirring for 1 hour. The reaction product maythen be added to a biguanide such as bi-- guanide itself, mono-phenylbiguanide or monobiphenylbiguanide in alcohol solution, preferably with the application of heat to complete the salt formation. 1

In practicing my invention any biguanide which in itself possesses soap stabilizing properties may be combined with p-tertiary amylphenyl phosphoric acid to form a salt, and in all cases it will be found that the stabilizing properties of the biguanide are improved. I prefer, however.

preferred compounds are preferably incorporated into the soap in amounts of about 0.01-0.2%, based on the weight of the soap, 0.1% being a suitable quantity. My invention will be described in greater detail by reference to the following specific example.

Example Fine white milled soap', having a neutralization number of 0.29, was ground and 0.1% of stabilizer was incorporated by adding 0.015 gram of the stabilizer to 15 grams of the soap. 150 cc. of hot, oxygen-free distilled water was then added and the mixture stirred with heating until the entire mass was dissolved. The solution was poured into a flat dish and cooled to a gel, which was dried to 10% moisture content. Three of the dried films were then united by pressure into a cylindrical cake about inches in thickness, using a hydraulic press and a pressure oi 2160 pounds per square inch for 15 minutes. The resulting soap bar was placed in a jar fitted with a screw cap. A number of samples containing.

'various soap antioxidants were prepared in, this .-tion before aging and T1 equals percent reflection after agin In all cases the results given were obtained after an aging time of seven days.

What I claim is:

rancidity by 'the presence therein of stabilizing amounts of a biguanide salt of a p-tertiary amylphenyl phosphoric acid, said soap being an alkali metal saltof a'fat acid.

2. Soap, stabilized against discoloration 0nd rancidity by the presence therein of stabilizing amounts of a mono-phenyi biguanide salt of a "p-tertiary amylphenyl phosphoric acid, said soap to use the p-tertiary amylphenyl phosphate salts oi the mono-aryl biguanides, and particularly the monophenyl and substituted monophenyl blguanm ides such as those enumerated above. These being an alkali metal salt oi a fat acid.

' mm w. 0001:. 

